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Brooks-British Range tundra

The Brooks/British Range Tundra ecoregion includes the mountainous belt that extends from almost the Chukchi Sea across northern Alaska and into northern Yukon Territory and extreme northwestern NWT. This ecoregion consists of three large areas connected along a continuum: the Western Brooks Range, with relatively low, less rugged mountains and less permanent ice; the Eastern Brooks Range/British Range, with higher, more rugged terrain and more permanent ice; and the lower area near Anaktuvuk Pass that divides the two mountainous areas. Elevations across the ecoregion range from 800 m to 2400 m, with peaks above 1800 m retaining the once-extensive Pleistocene glaciation (Pielou 1994, Gallant et al., 1995).

Arctic climate prevails, with temperatures decreasing with altitude. At Anaktuvuk Pass (the only long-term weather station in the region), the mean daily minimum temperature in winter is -30°C, mean daily maximum temperature in summer is 16°C, and annual precipitation is approximately 280 mm/year (Gallant et al. 1995). Temperatures at higher elevations are probably lower in both seasons. The mean annual temperature for the British-Richardson Mountains is -10°C, mean summer temperature is 6.5°C, and mean winter temperature is -25°C. Summers are short and cool, and winters are extremely cold but more moderate at higher elevations. Major mountain passes are subject to strong outflow winds, resulting in severe wind chill conditions. Mean annual precipitation is approximately 350 mm. The ecoclimate is described as alpine to subalpine northern subarctic Cordilleran. Glaciation, frost action and rapid erosion of steep, unstable slopes have kept soil accumulation low. Where they do accumulate, soils are predominantly Pergelic Cryaquepts, Pegelic Cyumbrepts, and Lithic Cryorthents.

In Canada, permafrost with low ice content is continuous in the southern half of the region, and ice content increases to the north. While the northern portion of the British and Richardson Ranges are unglaciated and peaks can reach an elevation of 1675 m, the southern parts of the ranges exhibit smooth, rounded profiles composed almost entirely of folded, sedimentary strata of Cambrian and Paleozoic origins. The ecoregion also contains a small portion of unglaciated topography composed of Tertiary sediments, and has some excellent examples of periglacial landforms (cryoplanation terraces and summits in particular) (ESWG 1995).

  • Scientific Code
    (NA1108)
  • Ecoregion Category
    Nearctic
  • Size
    61,600 square miles
  • Status
    Relatively Stable/Intact
  • Habitats

Description
Biological Distinctiveness
Due to the harsh, mountainous climate and terrain, vegetation cover is sparse, and restricted largely to valleys and lower slopes. Subalpine open woodland vegetation is composed of stunted white spruce (Picea glauca), and occasional alpine fir (Abies lasiocarpa) and lodgepole pine (Pinus contorta), in a matrix of willow (Salix spp.), dwarf birch (Betula spp.) and northern Labrador tea (Ledum decumbens). Alpine tundra at higher elevations consists of lichens, mountain avens (Dryas hookeriana) , intermediate to dwarf ericaceous shrubs (Ericaceae), sedge (Carex spp.), and cottongrass (Eriophorum spp.) in wetter sites. The highest latitudinal limit of tree growth (white spruce) in Canada is reached in the British-Richardson Mountains ecoregion (TEC 165). Wet to mesic sites contain mesic graminoid herbaceous communities (including Carex aquatilis, C. bigelowii, Salix planifolia and S. lanata), while drier sites support dwarf shrub vegetation (including Arcostaphylos alpina, Vaccinium spp., and Dryas octopetala) (Gallant et al. 1995). Dryas-lichen vegetation is common, with Dryas integrifolia or D. octopetala comprising 80-90 percent of the vascular plant cover (Bliss, 1988).

The Brooks and British Ranges straddle the migration routes of the porcupine, Central Arctic, and Western Arctic caribou herds (Rangifer tarandus). The herds generally migrate from north to south, following river valleys and traditional routes. They are therefore essential to the annual movements the caribou require, as well as to the free seasonal movement of grizzly bears (Ursus arctos) and wolves (Canis lupus). Other wildlife includes Smith's longspurs (Calcarius pictus), horned larks (Eremophila alpestris), Dall’s sheep (Ovis dalli), snowshoe hare (Lepus americanus), red fox (Vulpes vulpes), and Arctic ground squirrel (Spermophilus parryi) (McNab and Avers 1994). The eastern Brooks Range supports the northernmost breeding populations of golden eagles (Aquila chrysaetos) and gyrfalcons (Falco rusticolus) in the United States.

This mountainous region is extremely remote. Although used for subsistence and sport hunting, the ecoregion supports the full range of species characteristic of this area, including top level predators at viable population levels.

Conservation Status
The Brooks/British Range ecoregion is almost entirely intact. Two major highway corridors cross the ecoregion: the Dalton Highway (and oil pipeline), and the Dempster Highway. These structures can act as a barrier (or filter) to the movement of some species, but seldom an impenetrable one. Most historic caribou movements have paralleled the Dalton Highway and pipeline (north/south), but some groups, as well as bears and wolves, are known to move in an east/west direction as well. Both highways provide access to these mountains for hunters, and a buffer of hunting pressure exists bordering the road corridors. Other human disturbance is low, and has consisted of some mineral exploration and extraction. Wildfire occurrence is common, and fires average 17.9 km2 in size (Bailey et al. 1994).

The Red Dog lead-zinc mine, on the western edge of the ecoregion, is the largest development in the ecoregion. The size of reserves has recently doubled through additional exploration work and the mine has a projected life of 40 years. Ore is trucked along a road from the mine site to tidewater on the Chukchi Sea coast.

Degree of Protection
The protected area system captures a good range of mountain tundra habitat. The most important areas include:

•Gates of the Arctic National Park and Preserve - northern Alaska
•Noatak National Preserve - northern Alaska
•Kobuk Valley National Park - northern Alaska
•Ivvavik National Park - northern Yukon (partially in ecoregion) - 10,168.65 km2
•Vuntut National Park - northern Yukon (partially in ecoregion) - 4,345 km2
A number of Wild and Scenic Rivers have been designated throughout this ecoregion as well.

Despite this network of protected areas, one of the primary conservation priorities in this ecoregion is maintaining the freedom of movement for caribou and other large mammals. This cannot be accomplished simply by establishing and managing protected areas. The entire ecoregion, as well as those around it, must be managed to minimize barriers to these migrations and to other necessary movements.

Types and Severity of Threats
Major threats include:

•The possibility of mining activity. Some mineral exploration and small-scale extraction already have occurred.
•An increase in the hunting and recreation impacts on fragile tundra ecosystems and wildlife populations in the vicinity of the two roads, the Dalton and Dempster Highways.
•A continued steady increase in recreation activity in the National Parks. Again, fragile ecosystems with low resilience to human disturbance make this a concern.
Suite of Priority Activities to Enhance Biodiversity Conservation

•Manage entire ecoregion (and neighboring ecoregions) to maintain freedom of movement for caribou herds, brown bears, wolves, and other migratory or highly mobile wildlife. Prevent construction of barriers to migration such as roads or pipelines.
•Monitor development and recreation growth in National Parks and surrounding large lakes and rivers to ensure native fisheries are not being over-exploited and habitat damaged through overuse.
Conservation Partners

•Canadian Arctic Resources Committee
•Canadian Parks and Wilderness Society, Yukon Chapter
•Friends of Yukon Rivers
•Northern Alaska Environmental Center
•The Sierra Club, Alaska
•The Wilderness Society
•World Wildlife Fund Canada
•Yukon Conservation Society
Relationship to other classification schemes
This ecoregion combines Gallant (1995) ecoregion 102 and Ecological Stratification Working Group (1995) ecoregion 165. Major delineation features are the steep, high topography and sparse vegetation. Combination decisions based on Gallant et al. (1995), McNab and Avers (1994), Ecoregions Working Group (1989), and Viereck, et al (1992). The Canadian portion of the Brooks/British Range Tundra is in northern Yukon, extending slightly into the Northwest Territories. The corresponding terrestrial ecoregion is the British-Richardson Mountain region (TEC 165) (Ecological Stratification Working Group 1995). Vegetation in this region is primarily Tundra, with some Boreal Alpine (33) (Rowe 1972).

Prepared by: R. Hagenstein, T. Ricketts

 

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